A vulnerability has been identified in SIMATIC MV540 H (All versions < V3.3.4), SIMATIC MV540 S (All versions < V3.3.4), SIMATIC MV550 H (All versions < V3.3.4), SIMATIC MV550 S (All versions < V3.3.4), SIMATIC MV560 U (All versions < V3.3.4), SIMATIC MV560 X (All versions < V3.3.4). Affected devices cannot properly process specially crafted Ethernet frames sent to the devices. This could allow an unauthenticated remote attacker to cause a denial of service condition. The affected devices must be restarted manually.
https://cert-portal.siemens.com/productcert/pdf/ssa-561322.pdf